| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that, in an exhaust emission control device having a NOsensor at an upstream side of an exhaust passage rather than an SCRF, a NOconcentration cannot be accurately detected depending on a drive state of a vehicle.SOLUTION: In a control method of an exhaust emission control device 24 having an SCRF 24 for purifying NOcontained in exhaust gas, fuel adding means 24d for adding fuel to the exhaust gas which flows in an exhaust passage 23a from an upstream side rather than the SCRF 24, and a NOsensor 25 which detects a NOconcentration contained in the exhaust gas flowing between the fuel adding means and the SCRF 24, when it is determined that the NOsensor 25 is not in an active state, fuel is not added from the fuel adding means 24d until it is determined that the NOsensor 25 is in the active state even if there is necessity for adding the fuel from the fuel adding means 24d. |
